Fill valves in toilets provide water for refilling a toilet tank and for delivering water from the tank into the corresponding bowl during a flush cycle.
Current fill valves typically use floats in a form of an inverted cup or a ball that is disposed in a water tank to sense water level, so that when water level rises, the buoyancy formed on the float makes it rises to activate the valve to off position and when water level drops, the float drops under the gravity effect to turn the valve on. A first problem with such designs is that the float has to be in contact with water in the tank; therefore, debris or mineral deposit from tank water on the float create friction on the float motion, making it vulnerable to failure. An example of this is the traditional piston and ballcock design which has a relatively large float positioned on the end of a relatively long lever arm. One big disadvantage of these ballcock valves are the large amount of space they require to operate in the toilet tank. A long lever arm is required to generate enough force to overcome the hydraulic force through the fill valve in order to close the fill valve. A second problem with this float architecture is the float has to be in vicinity of the valve, in direct contact with the linkage mechanism to turn the valve on and off and float motion strictly obeys the law of gravity with only up and down motions, making this design less flexible for layout.
Another example of a traditional fill valve design is a pilot valve. Pilot valves are designed to improve upon the ballcock valves, wherein the pilot valve uses a smaller float to depressurize or pressurize a control chamber on top of a rubber diaphragm, which is used to seal against a larger opening for better flowrate, so that it can move one way or the other to open or to close the valve. Pilot valves, however, suffer from several noticeable shortcomings. For example, pilot valves are incapable of providing sufficient fast flow rate at substantially low pressures. On the opposite end, pilot valves tend to have higher water hammer at substantially high pressure. Another disadvantage of pilot valves is requiring a higher cracking pressure. The diaphragm of pilot valves is vulnerable to high pressure and/or chemical attacks, reducing its life over the piston type. Furthermore, the pilot valve typically requires tight tolerance parts to work properly. This type of valves with a smaller float still suffers from the same shortcomings by the effects of mineral deposit or requirement for float motion depended on gravity force.
Accordingly, a need exists to provide a fill valve which can be turned on and off without using the float architecture as is now required in traditional designs. It is also desirable to have fast flowrate at low pressures without compromising the life of the sealing member. It is also desired to provide a fill valve with a more compact design without external moving parts as compared to a large, bulky, traditional fill valve assembly. A small fill valve that occupies less space in the toilet tanks is desired. Finally, it is desirable that such a new fill valve would be more flexible for architecture layout to fit in different tank geometries.